Convert Grain to Ounce (gr → oz)

Converting grains to ounces is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in grains

   Start with the number of grains (gr) you want to convert.
2. 2
   Multiply by 0.002286

   The conversion factor from gr to oz is 0.002286. Multiply your value by this number.
3. 3
   Read the result in ounces

   The result is your value in ounces (oz).

Multiply the value in grains by 0.002286. For the reverse direction, multiply by 437.5.

• ✓1 grain = 64.79891 mg exactly. 7000 grains = 1 pound.
• ✓Ballistics is one of the few modern contexts where grains are essential.
• ✓Some older pharmacology dosing survives in grain units — 5 gr ≈ 325 mg.

• ✗Confusing the grain (mass) with the troy grain in older precious-metal contexts — they are identical (64.8 mg).
• ✗Assuming "grain" refers to an amount of cereal — in firearms it is always a weight.
• ✗Reading "5 gr" as 5 grams — it is 5 grains (324 mg).

What is the Grain?

The grain equals exactly 64.79891 milligrams (0.06479891 g) and is the smallest unit in the traditional avoirdupois weight system. Originally based on the average mass of a single grain of wheat or barley, the unit was standardized to its current value with the 1959 international yard and pound agreement. The grain is still used in pharmaceutical compounding (some older drug formulations specify grains, especially aspirin and codeine), arrow tips and ammunition (bullet weights are commonly given in grains — a 9 mm bullet is around 115 grains), and precious-metal weighing (one troy ounce = 480 grains). It relates to the ounce (437.5 grains = 1 oz avoirdupois), the pound (7,000 grains = 1 lb), and the milligram (1 grain ≈ 64.8 mg). The unit reflects medieval agriculture's role in shaping early measurement systems.

• Bullet and gunpowder mass in ballistics
• Older pharmaceutical dosing in Anglo-Saxon countries
• Arrow shaft and archery equipment weights

What is the Ounce?

The ounce equals exactly 28.349523125 grams or 1/16 of a pound. The word derives from the Latin 'uncia,' meaning one twelfth (the original Roman ounce was 1/12 of a Roman pound). The modern avoirdupois ounce, used for everyday weights in the United States and the United Kingdom, replaced the older Tower and Troy systems. It is the standard unit for American kitchen recipes (where 'ounce' refers to weight, distinct from the fluid ounce of volume), postal rates, package sizes (a 12-oz can of soda), and boxing-glove weights. Precious metals like gold and silver use the troy ounce (31.103 g), about 10% heavier than the avoirdupois ounce. The ounce relates to the pound (16 oz = 1 lb), the gram (1 oz ≈ 28.35 g), and the grain (1 oz = 437.5 grains).

• American and British cooking recipes
• Food packaging in the US
• Precious metals (troy ounce = 31.10 g, different from avoirdupois)